I took this photo south of El Pont de Suert in the Spanish Pyrenees whilst mapping there
last summer. We saw everything from metamorphic schists formed as a result of extreme heat and pressure in the Variscan orogeny to ignimbrites, which form as a result of pyroclastic flows during explosive volcanic eruptions.
In some places the entire sequence was upside down! This is due to the folding and faulting that occurred in the Alpine orogeny, forming the Pyrenees among other mountain belts; in the background of this photo it is possible to see some very steeply dipping beds which evidence this.
Image: Amber Madden-Nadeau